Lamp

Abstract

A bandpass filter comprises an air filled aluminum chamber having a lid and a cuboid resonant cavity having a central iris. At opposite end nodes of the cavity, perfect electric conductors (PECs) are provided. Threaded tuning projections opposite the PECs and in the iris are provided, whereby the pass band and the transmission characteristics of the filter in the pass band can be tuned to match the input impedance of the band pass filter and the wave guide to the output impedance of a microwave drive circuit. It is mounted on one end of the filter chamber, with an electrodeless bulb in a central cavity directed axially away from the chamber and the radiator in a further cavity set to one side of the central cavity. When the filter is driven, the wave guide resonates driving the bulb.

1. A lamp to be driven from a source of microwave energy, the lamp comprising:
 an electrodeless discharge bulb; 
 a radiator for radiating microwave energy to the bulb; 
 a bulb receptacle formed of ceramic material coated with an electrically conductive shield, the receptacle comprising:
 a first recess containing the bulb, the recess being open to allow light to shine from the bulb, and 
 a second recess containing the radiator, with the second recess being open to allow connection of microwaves to the radiator; and 
 
 a microwave circuit comprising:
 an input for microwave energy from the source thereof; 
 an output for connect thereof to the radiator in the ceramic receptacle; and a combination of the input, the output, the receptacle and the bulb, 
 
 
       wherein the microwave circuit comprises:
 a capacitative-inductive circuit configured as a bandpass filter and matching output impedance of the source of microwave energy to input impedance of the capacitative-inductive circuit, receptacle and bulb combination; and further comprises 
 a tunable comb line filter; and 
 
       wherein the microwave circuit comprises:
 a metallic housing; 
 a pair of perfect electric conductors, each grounded inside the housing; 
 a pair of connections to the perfect electric conductors, one for input and the other for output, and 
 a respective tuning element provided in the housing opposite the distal end of each perfect electric conductor. 
 
     
     
       2. The lamp as claimed in  claim 1 , further comprising an addition tuning element provided in an iris between the perfect electric conductors. 
     
     
       3. The lamp as claimed in  claim 1 , wherein the metallic housing is plated internally to a skin depth of six microns or more with high electrical conductivity metal. 
     
     
       4. The lamp as claimed in  claim 1 , wherein the dielectric material between the elements of the microwave circuit is air. 
     
     
       5. The lamp as claimed in  claim 1 , wherein the dielectric material between the elements of the microwave circuit comprises a ceramic material. 
     
     
       6. The lamp as claimed in  claim 1 , wherein the bulb receptacle comprises a resonant wave guide. 
     
     
       7. The lamp as claimed in  claim 1 , wherein the bulb receptacle comprises a resonant half wave guide. 
     
     
       8. The lamp as claimed in  claim 6 , wherein the resonant wave guide comprises a material having a dielectric constant greater than one. 
     
     
       9. The lamp as claimed in  claim 7 , wherein the resonant half wave guide comprises a material having a dielectric constant greater than one. 
     
     
       10. The lamp as claimed in  claim 6 , wherein the resonant wave guide comprises a ceramic material. 
     
     
       11. The lamp as claimed in  claim 7 , wherein the resonant half wave guide comprises a ceramic material.